Has biwire speaker cabling become "old" ?

Funny thing, my Dunlavy speakers have bi-wire terminals. If he didn't believe in them why did he put them on his speakers?
Rja

Because some marketing types told him audiophiles demand it.

Anytime you can keep signals separate it's usually a good things. The signals are different on each run and it's night to keep them away from each other if you can. Higher resolution systems will shows the differences most of the time.
Ctsooner

Not sure where you got this information, but if you are biwiring using only one amp, the signal is identical on both cables.

03-20-15: Rja
Funny thing, my Dunlavy speakers have bi-wire terminals. If he didn't believe in them why did he put them on his speakers?

Speaker designers do this for many reasons. Bi-amping is a higher priority reason that speaker manufacturers use multiple binding posts than bi-wiring though. Another reason is marketing, and meeting consumer demand.
Believe it or not, some people won't buy speakers if they can't bi-amp/bi-wire.

My 25 yr old Spendor S100's are configured for TRI-wiring and I've been doing so for over a decade! I recall hearing a difference for the better when I 1st went 'tri' over a decade ago but haven't felt the need to experiment in quite some time. Honestly, I'm one of those audiophiles that 'plateaued' a while ago. To me, my rig sounds glorious, so now I concentrate on spending my money on the music.

When one's system reaches a certain level of transparency, running your speakers bi-wired is worthwhile. This means not only are your components compatible with each other, EMI/RF is not a major problem, system cabling is off the floor and neither coiled nor bundled, racking and support are sturdy, contacts are clean, clean AC power is available, the room isn't plagued with standing waves anymore, and lots of other little things that have a bigger impact collectively have already been addressed. Until then, you will probably be disappointed with the return for bi-wiring.

I have been bi-wiring for 25 years after hearing how much better everything sounded. I economized on speaker cable by setting my amps back-to-back with the speaker terminals and bought the best possible wire in the shortest possible lengths. I started with Cardas Hexseries that ran about $2500 for 2 1/2 meter pairs. These ran between Atma_sphere 100w OTLs and a pair of Snell B-types. They end in Rhodium plated spade lugs. The Binding posts on the speakers and amps had been upgraded to Edison Price. The system had very good analog sources over the years and sounded outstanding to me all that time, But, I could never hear the difference when I experimented with things like running only one speaker cable, until after I had retired and could only afford relatively cheap tweeks and changes to the system. It was only after I had cleaned up some of the nasties I listed above that the system became transparent enough to show that bi-wiring is best.

I retired the Cardas cables two years ago in favor of a really superb 1m biwire set of flat solid silver ribbon biwire cables from Ridge Street Audio. These are designed to maximize sound purity through simplicity in design. They are designed so that the bass leg is significantly larger than the one for the mids and highs.

Unfortunately, due to a recent speaker upgrade - I retired the Snells this Winter with a pair of Genesis 6.1. The new speakers are meant to be run full-range from a single set of binding posts. The best sound is said by the manufacturer to come from letting the speaker's electronics split the highs from the speaker cable rather than running an RCA or balanced interconnect. So, I have now put another superb set of cables on the back shelf.